The present invention relates to improvements in methods of and in apparatus for actuating torque transmitting systems in the power trains of motor vehicles. The torque transmitting systems adapted to be actuated in accordance with the method and by the apparatus of the present invention can constitute friction clutches or other types of clutches including magnetic powder clutches and hydrokinetic torque converters with bypass or lockup clutches.
More particularly, the invention relates to improvements in methods of and in apparatus for automated actuation of torque transmitting systems (hereinafter called clutches for short) in power trains of the type wherein a clutch can be utilized to transmit torque from a prime mover (such as an internal combustion engine) to a manual, automated or automatic transmission or from the transmission to one or more driven units.
It is known to actuate a clutch in the power train of a motor vehicle by resorting to an arrangement (herein-after called actuator) which receives signals from one or more sensors and/or electronic circuits and employs an actor (e.g., a hydraulic actor utilizing a master cylinder and a slave cylinder) which transmits motion to the actual clutch engaging and disengaging means, e.g., to the resilient tongues or prongs of a diaphragm spring in a friction clutch wherein the diaphragm spring can be caused to urge a pressure plate toward an engine-driven counterpressure plate so that the two plates clamp the friction linings of a clutch disc which serves to transmit torque to the input shaft of a manually or otherwise operated transmission when the clutch is engaged. The actor at least partially engages or disengages the clutch in response to signals from the sensor or sensors and/or from the electronic circuit or circuits.
It is also known to design the actuator in such a way that it becomes operative in response to turning on of the ignition system for the engine of a motor vehicle, and it is equally known to provide a motor vehicle with means for reliably holding a parked or otherwise stored or idled vehicle against undesired rolling movements, e.g., during parking on a sloping surface on a road or in a garage. For example, certain vehicles are provided with safety systems which ensure that the clutch is automatically engaged when the actuator is inoperative so that the turned off engine acts as a brake in that it opposes rotation of the clutch disc in response to the tendency of the vehicle wheels to roll along an incline. When the ignition system for the engine is turned on, the actuator for the clutch becomes operative.
As a rule, the operator of a vehicle will use one and the same hand first to insert the ignition key in order to render the actuator operative, to thereupon manipulate a lever in order to shift the transmission from a forward or rearward gear into neutral, and to thereafter turn the ignition key in order to start the engine. Such mode of operation with one hand provides a considerable amount of safety but is not overly convenient to the operator of the motor vehicle.